//
// Created by Joey on 2019/12/17.
//
#include<iostream>

using namespace std;

const double PI = 3.14;

class Circle {
public:
    int m_r;

    double calculateZC() {
        return 2 * PI * m_r;
    }
};

int main() {

    Circle c1;
    c1.m_r = 10;

    cout << "圆的周长为：" << c1.calculateZC() << endl;

}

